On Wed, Oct 21, 2015 at 2:00 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: .... >>>> To put a few more numbers on the "chunk size vs perf": >>>> 1EG (512KB) -> 44K commands -> ~20 minutes >>>> 32EG (16MB) -> 1375 commands -> ~1 minute >>>> 128EG (64MB) -> 344 commands -> ~30 seconds >>>> 8191EG (~4GB) -> 6 commands -> 2 seconds + ~8 seconds mkfs >>>> (I'm assuming times above include about 6-10 seconds of mkfs as part >>>> of writing a new file system) >>>> >>>> This is with only ~300MB of data written to the partition. I'm fully >>>> aware that times will vary depending on how much data needs to be >>>> migrated (and in this case very little or none). I'm certain the >>>> difference will only get worse for the smaller the "chunk size" used >>>> to Secure Erase due to repeated data migration. .... > I am not sure if this issue is the same as been discussed earlier on > the mmc list regarding "discard/erase". > > Anyway, there have been several attempts to fix bugs related to this. > One of these discussion kind of pointed out a viable solution, but > unfortunate no patches that adopts that solution have been posted yet. > > You might want to read up on this. > https://www.mail-archive.com/linux-mmc@xxxxxxxxxxxxxxx/msg23643.html > http://linux-mmc.vger.kernel.narkive.com/Wp31G953/patch-mmc-core-don-t-return-1-for-max-discard > > So this is an old issue, which should have been fixed long long long time ago... Agreed. :) I'll read the references but hope that Gwendal (or someone on Android Team?) can follow up on this shorter term. I've moved to a different team (Google Onhub) and currently have a whole new set of (wireless) issues to deal with. :( At some point I expect I'll be circling back to mmc issues - storage keeps following me like a hungry puppy where ever I go. /o\ thank you! grant -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
